In many industries, there is frequently a requirement for the separation of solid materials and objects from liquids, and many techniques are well known for achieving such separations. Depending upon the nature of the solids and liquids which require separation, and the quantities involved, methods such as sedimentation, centrifugation and, most commonly, filtration are generally appropriate to such situations and provide an efficient means of separating solid and liquid components.
On occasions, however, such methods may prove to be inappropriate to the task at hand, and alternative means of separation have to be found. Thus, for example, centrifugation may not always be applicable to large scale separations, whilst filtration is often problematical when handling particularly viscous liquids, since rates of filtration can be excruciatingly slow, making processes uneconomic; indeed, in extreme circumstances, the method may prove to be impossible to perform, since filter media become clogged and liquids are unable to pass through. Indeed, when mixtures of very high viscosity are involved, it is often impossible to achieve any sort of separation by means of filtration techniques, since it becomes impossible to find filter media of appropriate gauge to allow a liquid component to pass whilst retaining solid materials in the filter, so either the filtrate comprises all components, nothing is retained in the filter, and no separation is achieved, or the filter media becomes immediately blocked, with the same end result. Even the filtration technique often known as screening, which relics on filtration of a medium through coarse screens, can be prone to such difficulties. It is these problems with viscous media that the present invention seeks to address, by providing a method of separation which allows for the separation of solid components from such media.
A typical prior art method for dealing with such difficulties has been based on the reduction of the viscosity of these highly viscous media prior to attempting separation, and the simplest means to achieve such an objective is by dilution of the media. Most conveniently, of course, dilution is achieved by the addition of water, which is a simple and relatively cheap procedure. However, whilst such a course of action is often successful in facilitation separation of components, since the less viscous medium obtained is generally more readily subjected to processes such as filtration, the associated consequences are highly undesirable, since copious quantities of effluent—usually aqueous effluent—have to be dealt with following the separation process. Hence, a further consideration of the present inventors is the minimisation of effluent problems by the avoidance of dilution techniques in the method of the invention.
Thus, the present invention seeks to provide a method by which solid objects and components may, rapidly and efficiently, be separated and removed from viscous media, including highly viscous, non-filterable sludges. The invention also seeks to provide a method which provides a reliable and repeatable means of effecting the separation of such materials, and which is not prone to the failures commonly associated with the methods of the prior art in such circumstances.
The present inventors have investigated the use of mechanical forces which selectively impart momentum to the components of said media for the purpose of achieving the required separation and, somewhat surprisingly, have found that it is possible to achieve such separation by the application of vibrational technology, since it has been found that, in certain vibrational modes, a suitably disposed surface shows the degree of selectivity in imparting momentum which is required to achieve the separation of solid objects and components from viscous media.